Circuit breaker



Sept 8, 1936.

Deu/icl CPrince ttorneq lPatented Sept. 8, i936 UNITED STATES PATENT OFFICE CIRCUIT BREAKER New York Application February 18, 1935, Serial No. 7,085

25 Claims.

My invention relates to circuit breakers of the typ-e which is manu'ally operable between on and oii" positions and in response to overload current is automatically operable to an open circuit position, and has for an object the provision of a reliable, inexpensive ,and compact circuit breaker.

More particularly, my invention has for its object a spring snap acting operating mechanism for circuit breakers wherein the operating force required to operate manually the circuit breaker between openand closed positions is greatly decreased, while the biasing force on the movable contact remains lat a high value. y

Further objects of my invention are the provision of means associated with the manually operated mechanism for rigidly engaging the movable contact to initiate positively its movement at substantially the same time that the spring snap acting mechanism is rendered effective, and means for returning the handle to a mid-position upon overload opening of the breaker.

My invention has particular application to circuit breakers provided with overcenter spring snapping mechanism wherein a. pivotally mounted operating handle is provided for moving one end of the overcenter spring from one side to the other of a dead center position to eiect snap movement of the movable contact. It is advantageous in a device of this character to provide a pivoted handle which is relatively short in order that its arc of movement between the on and oi positions may be relatively great. It will be yunderstood that one end'of theovercenter spring is ordinarily attached to the pivoted operating memberat some point spaced from its pivot. This arrangement has the disadvantage that due to the substantial angle between the handle and the spring, the spring applies a force ofl very considerable magnitude in opposition to movement of the handle.

In carrying out my invention I greatly reduce the Yforce appliedby the spring to the handle by providing an intermediate relatively long pivoted link or arm extending lengthwise of the spring and to the movable end of which the movable end of the spring is attached. 'I'his arrangement provides for the required range of movement of the end of the spring with but little angular displacement between the spring and the link and, consequently, the spring oiers but little opposition to movement of the link. I also provide an operating connection between the handle and the relatively long link whereby I obtain the advantages of 'a relatively short operating handle and lower required operating force.

I also provide a positive operating connection between the intermediate link and the movable contact whereby the contact is forcibly moved at 5 substantially the same time that the overcenter spring becomes eiective to continue the movement of the contact. This feature is of particular advantage in opening the breaker since the initial positive movement of the contact assures separation of the contacts for snap action by the'spring even though they may be welded together from any cause, such as arcing.

I furthermore pivotally mount the xed end of the intermediate link at a point within the range of movement of the movable contact. By means of this arrangement I provide for a reversal of the bias of the overcenter spring on the link upon movement of the switch to the openy position in response to overload conditions so that the link, and through it the handle,.is iinally biased to the oi position and is brought to rest in a mid-position. This mid-position of the handle furnishes an indication of the overload opening of the circuit breaker.

For a more complete understanding of my invention, reference should now be had to the drawing wherein I have shown in Fig. 1 an elevation, partly in section, of a circuit breaker ernbodying my invention; Fig. 2 illustrates the circuit breaker of Fig. 1 but with the parts in the positions assumed at the instant the link rigidly engages the movable contact; Fig. 3 illustrates the circuit breaker of Fig. 1 after it has been tripped in response to an overload and before the handle returns to the mid-position; Fig. 4 illustrates the circuit breaker of Fig. 1 after the handle has been automatically moved to the mid-position; and Fig. 5 is a fractional elevation taken on the line 5--5 of Fig. 1.

Referring to the drawing, I have shown my invention in one form as applied to a circuit breaker I0 of thetype described and claimed in a copending application of Ludwig S. Walle, Serial No. 667,856, filed April 25, 1933, entitled Circuit breake and assigned to the same assignee as the present invention. The invention of said Walle application was made prior to my invention and I do not herein claim anything shown or described in said Walle application which is to be regarded as prior art with respect to this present application.

Referring to Figs. 1 and 4, the circuit breaker I0 is provided with a base I l and a cover l2, both formed of insulating material. The operating mechanism for operating aslidably movable contactv I3 between open and closed circuit positions' with reference to a stationary contact I3 is mounted upon a U-shaped metallic frame I5 suitably` secured to the base II as by screws (not` shown). An operating member or handlev I6 is carried by a support Il formed of sheet metal which is mounted on a pivotpin I8 carried by 4the frame. The handle I5 is operable between on and off positions to effectuate a snap action of the movable contact I3 by means of a pair of overcenter springs I9 and 20 which are normally under a predetermined tension. The eort required to operate the handle I6 is minimized by supporting corresponding ends of the overcenter springs on the respective ends of a pin 2I extending -through a longitudinal slot 22 provided -in the handle and supported on corresponding ends of a pair of relatively long links 23 and 26 which are pivoted respectively at their opposite ends on a pivot pin 25 supported by the frame I5. `'I'he opposite ends of the overcenter springs I9 and 20 are secured to the respective ends of a pin 26 extending through slots 27 provided in theV frame and through a slot (not shown)` provided in the movable contact, the pin 26 being carried bythe spaced free end of a guide link 28. which end straddles one 'end of the movable contact I3. 'I'his guide link, pivoted at its opposite end on the pivot pin I8, is shown as consisting of two parallel links or portions joined into a unitary member by a cross connecting portion 29 which cooperates with an 'overloadtripping member 30.

This member 30, pivoted at4 I8, is normally restrained against movement by an overload tripping spring 3I by means of a bimetallic thermal element 32 formed of dissimilar metals and which is connected in circuit with the movable contact I3 by means of a flexible shunt or conductor 33. In order to operatethe circuit breaker to the open circuit position, the handle I6 is moved from the on to the oi position. The resulting movementv of the overcenter springs i9 Vand 20 past the dead-center position determined by the pivot pin I8 reverses the bias applied to the movable contact I3 and causes it to operate with a snap action to the open circuit position.

If the pin 2l and the overcenter springs I 9 and 20 were 'supported by the relatively short handle I6, the full force of the springs would apply' aV torque to the handle the magnitude of which,4

would depend on the angular displacement between the handleand the spring, i. the shortest distance between the line of raction of the springs and the center of the pivot pin I 8. With the required movement of the relatively short handle between on and o' positions, `the pin moves through a relatively wide angle with a correspondingly large angular displacement between the handle and the spring. With this arrange-r ment the requiredhandle operating rforce due to the initial wide angular displacement and the relatively great increased elongation of the springs' upon movement of the handle was so great as to be quite objectionable, particularly when a plurality of mechanisms were simultaneously operated by a single handle.

In accordance with my invention, however,

. the links 23 and 24 by supporting the pin 2l and the ends of the overcenter springs greatly reduce the spring force applied to the handle I6. Inasmuch as the lrigid links 23 and 24 are substantially in line with the overcenter springs I9 and `2l), thelonly'biasing force applied to the handle.

is the component of `force which tends to rotate aosaovi the nnks 2s and 2i. The resuming-torque wur.

vary with the angle between the springs and the links, i. exwith the distance that the axis of the pin 25 is separated from the line of action of the overcenter springs I 9 Vand 20. Preferably, thedistance is relatively small Jwith the handle either in the on or the 'oi position. Since a relatively small torque is applied to the handle I 6 by the springs, it follows that only a relatively small torque is necessary tov move the handle I6 between the on and oi positions. y

The slot 22 in the handle supporti? extendsalong a radialline of the handle and forms in conjunction with the pin 2I a lost motion driving connection withl the links 23 and 23. Upon rotation of the handle I6 the pin 2l and the ends of the overcenter springs I9 and 20 rotate in a relatively iiat arc which is determined by thev length of the links 23 and 2li. Consequently, the overcenter springs are not materially elongated as the handle is moved towards its mid-position This decreased operating force becomes of even greater importance in 'connection with multipole circuit breakers provided with a plurality of' operating mechanisms. Such multipole circuit breakers when constructed in accordance with the lpresent invention-can be operated with substantially the same eort that is required to operate af'single pole circuit breaker of the old type. n'

Under some conditions of operationy the movable contact-I3 may have a tendency to become welded to the stationary contact IQ due to arcing between the contacts. In order to insure' the positive opening of the contacts under such abnormal conditions, I provide slots in the respec- \tivelinks 23 and 24, only one slot, i. e. 36', in *the link 23 being shown. 'I'he slot in the link 24, however, is identical with the slot 313. 'I'he relation between the pivot pin 25, the slots, and

the over-center springs I9 and 20 is such that the walls of the slots in the links 23 and 23 rigidly engage the pin 26 at substantially the same instant that the over-center springs are moved f past the dead-center position determined by the axis of the xed -pivot pin I8. 'I'his relationship of the parts is shown in Fig. 2. A slight additional movement of the handle I6 towards the.

ofi position causes the links 23 and 23 to move the contact I3 forcibly away from the stationary contact I4. .At the same instant the over-center yto springsv I9 and 20 accelerate the movable contact I3 to the open circuit position. This position is determined by the engagement vof the pin 26 with the sides-of the slots- 2l providedy in the U-shaped frame I5, the movable contact I3 having a range of movement between its open and closed circuit positions.

` Besides positively initiating movement of the contact I3 from the closed towards the'open position, the links 23 and 2B serve to initiate movement of the contact I3 toward the closed circuit position, the pin 26 as shown in Fig. 4 then engaging the links at the opposite ends of the slots. The result is a higher closing speed for the movable contact inasmuch as the over-center springs I3 and 2l! accelerate the movement of the contact I3 more than they would if the acceleration of the contact were initiated from standstill. As the handle I6 is moved from the off to the on position, the movable contact I3 is first moved by the links 23 and 2Q and as the over-center springs I3 and 2li are moved past their deadcenter position the movable contact I3 is accelerated to the closed circuit position. In order to obtain uniformity in operation in the two directions the xed axis of the links, i. e. the axis of pivot pin 25, is located substantially midway of the range of movement of the movable contact I3.

It should here be noted that the relatively long links 23 and 24 with their respective slots 1ocated fairly close to their xed axis or pivot pin 25 provide a substantial mechanical advantage to multiply the force of the handle as applied to the movable contact I3. An additional mechanical advantage is secured, which also minimizes the effort required to operate the handle I6 between on and olif positions, by reason of the diierence in the length of lever arms of the handlev I6 on pinv I8 and the pin 2| on the pin I 8. Consequently, the outer end of the handle .I6 when rotated through a given angle moves a greater distance than the pin 2I and the free ends of the links 23 and 24.

In case of an overload, the heat produced in the bimetallic thermal element 32 by the current causes sufficient ilexure of the thermal element to release the overload tripping member 30. Preferably, the thermal element is U shaped and has its two ends secured respectively to terminal lugs 35 and 36, whereby it is supported, its middle or base portion 3'I normally engaging and holding the tripping member 33. As soon as it is released, Fig. 3, the overload tripping spring 3l rotates the tripping member 36 in a clockwise direction, as viewed in the drawing, until a projectin'g end 33 of the tripping member rigidly engages the cross portion 23 of the guide link 26 and rotates the guide link 28 in a direction to move quickly the contact i3 to the open circuit position against the bias of the over-center springs I3 and 2li.

After the overload opening of the circuit breaker has been initiated, the pin 26 secured to the movable contact is operated across a line taken between the pivot pins 2l and 25. With the circuit breaker in the closed circuit position, the pin 26 is located on one side of the line taken through the centers of the pivot pins 2i and 25 so that the over-center springs I 9 and 23 bias the links .23 and 24 in a clockwise direction, the extent of clockwise rotation being limited by the engagement of the links with the base Ill, as'

indicated at 39. However, as soon as the pin 26 is moved to the opposite side of the line taken through the pins 2| and 25. the bias of the overcenter springs I9 and 20 is applied to the links 23 and 24 in a direction to rotate them in a counter-clockwise direction. 'Ihe result is that -the links 23 and 24 operate the handle I6 from the on position -towards theroif position as soon as the pin 26 crosses the line determined bythe pins 2l and 25. In this manner the over-center springs perform a` double function. The movement of the ends of the Asprings I9 and 20 attached to the pin- 2I from one side to the other of the dead-center position or pivot I8 operates the movable contact I3 with a snap action. Similarly, movement of the opposite ends of lthe springs I9 and 20 past a dead-centerposition determined by the fixed axis of the pivot pin 25 reverses the bias on the links 23 and 24 which reversed bias operates the links and the handle from an on towards the off position.

By utilizing the two dead centers determined by the xed axes of the pins I8 and 25, the handle I8 canl be returned to the oif position by a relatively small movement of the pin 26. The movement required may be decreased by locating the pivot 25 nearer to the line taken through the centers of the pins 2l and 26 when in the positions shown in Fig. l.

As the handle I6 is moved by the over-center springs I3 and 2li from the on towards the oi position, the tripping member 36 approaches the handle I6. The arrangement is such that the handle I6 and the tripping member 3i) come into engagement at substantially the instant that the handle I 6 arrives in a position intermediate its on and oi positions and the movable contact I3 reaches its open circuit position, as shown in Fig. 4. The intermediate or mid-position of the handle affords a very convenient and satisfactory means of indicating the overload operation of the circuit breaker.

1n order to reclose the circuit breaker, the oper- -ating handle is rotated in a counter-clockwise dle to the mid-position and thereby prevent the closure of the circuit breaker. However, as soon as the tripping member 3l) is relatched by the bimetallic thermal element 32, it is necessary only to operate the handle i6 from the olf position to the on position to close the circuit breaker. It will be observed that the circuit breaker is tripfree, that is to say, the movable contact I3 can not be maintained in engagement with the stationary contact I4 when an overload occurs because the tripping member 30 when releasedby the thermal element 32 is operated by the tripping spring 3l to open the circuit breaker irrespective of the position of the handle I6 or the bias of the over-center springs I9 and 2li.

While I have shown a particular embodiment of my invention,l it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, therefore, conf 1. A circuit breaker comprising a switch member movable between open and closed circuit positions, an operating handle provided with a relatively short radiusfor movement about a yfixed axis between on and ofi positions, an over-center spring operatively connected at one end to said switch member, and means including a driving connection between'said handle and the opposite end of said over-center spring for moving said opposite end of said over-center spring through an arc the radius of which is substantially greater than said radius of Asaidoperating handle.

2. Anoperating mechanism comprising a memvfixed end pivotally mounted within said range f ber having a predetermined range of movementl between predetermined positions, a link having a of movement and a free end movable between` predetermined positions, an over-center spring having one end operatively connected to saidI member and the opposite end connected to said free end for operating said member with a snap action when. said ,free end of said link is moved from one to the other of its predetermined positions, and means for moving said member independentlyof said link, the range of movement of said member, the predetermined positions of said link,fand the fixed end ofsaid link being so' related that movement o f said one end of said over-center spring with respect to said -xed end of said link when said memberis moved from one to another of its predetermined positions independently of said link is effective to reverse th bias applied by said spring to said link.

3. A circuit breaker comprising a switch member movable between open and closed circuit positions, an over-center spring having one end operatively connected to said switch member, an operating member operable between on and o positions for moving the opposite en d Iof saidl spring to operate said switch member, supporting means for said opposite end of said spring for fmaintaining said spring under a predetermined stress, a driving connection between said sup` porting means and said operating member, and means including said driving connection for minimizing the application of the force of said spring on said operating member.

4. A circuit breaker comprising a switch member having a range of movement between open and closed circuit positions, an over-center spring operatively connected at one end to said switch member, a link pivotally supported at one -end within the range of movement of 'said switch off positions, a link having a ixed end pivotally mounted within said range of movement of said switch member, the opposite free end of said link being operatively connected to said operating member, an over-center spring one end of which is operatively connected to said switch member and the opposite end of which is operatively connected to said free end of said link, said operating member when moved between said on and oi positions `operating said spring to move with a snapaction'said movable contact/between said open and closed circuit positions.

6. A circuit breaker comprising a switch member having a range of movement between open and closed circuit positions', an operating member having a range of movement between on and E positions, a link having a xed end pivotally mounted within said range of movement of said switch member, the opposite free end of said link being loperatively connected to said operating member, an over-center spring one. end of Whichis operatively connected to said switch member and the opposite end of which is operatively connected to saidvfree end of said link, said -operato ing member when moved between said on and oi positions operating said spring' to move with a snap action said movable contact between said open and closed circuit positions, and means for operating said movable contact from closed circuit position towards said open circuit position and beyond said xed end of said 'link to reverse the bias of said over-center spring on said link to operate thereby said operating member from said on position towards said oi position.

VV'1. A circuit breaker fcomprisingcontacts one of which is movable relative to'the other between `open and closed. circuit positions, an. operating handle, pivot means for mounting said handle for movement between on and oi positions, said handle being provided with a slot extending substantially parallel to the radius of the handle, a relatively long link pivoted at one end, its opposite free end bei'ng operatively connected to said slot,

and an over-center spring one end of which is connected to said free end of said link and the opposite end of which is connected to said movable -mounted within said range of movement of said switch lmember and theopposite free end of said link being operatively connected to said operating member, an over-center spring one end-of which is operatively connected to said switch member and the opposite end of which is operatively connected to said free end of said link, said operating member when moved between said on and oi positions operating said spring to move with a snap' action said movable contact between said open and closed circuit positions, means for operating said movable contact from closed circuit position towards said open circuit position and beyond said fixed end of said link to reverse the bias of said over-center spring on said link to operate thereby said operating member .from said on position towards said 01T position,

and means for stopping said operating member between said on and oi positions.

9. A circuit breaker comprising contacts, one of ywhich is movable relative to thev other between open and closed circuit positions, an operating handle, means pivoting said handle for movement between on and oi positions, said handle being provided with a radial slot, a link pivoted adjacent Said movable Contact, connecting means forming a driving connection between the sidesof said slot and said link, an over-center spring one end of which is operatively connected to said movable contact and the other end of which is supported by said connecting means so that when said handle is moved between on and oi positions-said end of said over-center spring connected to said connecting .means moves through an arc determined by the length of said link.

10. A circuit breaker comprising contacts, one of whichis movable relative to the other between open and closed circuit positions, an operating member therefor, pivot means mounting said member for movement between o n and 01T positions, said member being provided with a radial slot, a link, connecting means carried by one end of said link and forming a driving connection with the walls of said slot, pivot means mounting the opposite end of said link adjacent the said moving means and to said movable contact, the relation of said pivot means for said member and said l link being such that said over-center spring biases said movable contact in said closed circuit position and said member in said on position, means for operating said movable contact and one end of said spring towards said open circuit position to reverse the bias which said over-center spring applies to said link whereby said operating member is moved towards said oi position, and means for bringing said operating member to a standstill in a position. intermediate said on and oi positions.

il. A circuit breaker comprising contacts, one of which is movable relative to the other between open and closed circuit positions, an operating member therefor, pivot 'means mounting said member for movement between on and on positions, said member being provided with a radial slot', a link, connecting means carried by one end of said link and forming a driving connection with the walls of said slot, pivot means mounting the opposite end of said link adjacent to said movable contact, an overceriterr spring connected between said connecting means and said movable contact, the relation oi said pivot means for said member and said link being such that said overcenter spring biases said movable contact in said closed circuit position and said handle in said on position, and means for operating said movable contact towards said open circuit position and to a position to reverse the bias applied by said overcenter spring to said link whereby said link is rotated in a direction to move said operating member towards said oi position. y 12. A circuit breaker comprising a switch memberA having a range of movement between open and closed circuit positions, an over-center spring connected at one end to said switch member, a link one end of which is pivoted for rotation about a xed axis located within the range of movement of said switch member, an operating handle movable about a xed axis between on and on positions, a guide member one end of whichis movable about a xed axis and the opposite end of which is connected'to said switch member, and connecting means forming a driving connection between said handle and the opposite ends of said link and said over-center spring.

13. A circuit breaker comprising a switch member having a range of movement betweenl open and closed circuit positions, an over-center spring operatively connected at one end to said switch member, a link having one end rotatable about a fixed axis located within the range of movement of said switch member, an operating handle operable about a xed axis between on and oi positions, said fixed axis being located on one side of said range of movement and said fixed v axis for said link being located on the opposite side of said range of movement, a guide member having one end pivoted about a nxed axis and its opposite end connected to said switch member, and connecting means forming a driving connection between said handle and the opposite ends of said link and said over-center spring, said handle being provided with a slot forming a 'lost motion connection to provide for relative movement of said connecting means with reference to said handle.

i4. A circuit breaker comprising a' switch member having a range of movement between open and closed circuit positions, an over-center spring l connected at one end to said switch member, `a

link of greater length than said over-center spring, one end of said link being mounted for rotation about a xed axis, an operating handle mounted for rotation about a xed axis between on and 01T positions, a guide member pivoted at one end about a xed axis and connected at its opposite end to said switch member, and connecting means forming a driving connection between sa'id handle and the opposite ends of said link and said over-center spring, said handle being provided with a slot to provide for movement of said connecting means to minimize thereby the effort required to move said-handle between said on and oi' positions.

l5. A circuit breaker comprising a switch member having a range of movement between open and closed circuit positions, an over-center spring connected at one end to said switch member, an operating handle movable about a fixed axis between on and off positions, a link pivotally supported about a xed axis remotely located from said axis for said handle, connecting means for supporting the opposite ends of said over-center spring and forming a driving connection with said handle, said connection including a slot4 whereby the elongation of said spring when said handle is moved between on and orf positions is determined by the length of said link.

ber having a range of movement between open and closed circuit positions, an operating handle pivoted for movement between on and oli positions, said handle being movable about a relatively small radius, a link pivotally supported at one end within the range of movement of said switch member the opposite free end of said link being movable lthrough a relatively at arc, connecting means forming a driving connection between said free end of said link and said operating handle, said cornecting means including a slot to provide relative movement between said connecting means and said handle, an over-center spring connected at one end to said switch member and at its opposite end to said connecting means so that when said handle is moved between Y said on and 0E positions said over-center spring mined solely-by the radius of said link.

17. A circuit breaker comprising a switch member having a range of movement between open and closed circuit positions, an operating member having a range of movement between on and oft positions, a link having one end mounted above a fixed axis within said range of movement of said switch member and the opposite free end of said link being operatively connected to said operating member, an over-center spring having one end operatively connected to said switch member and the opposite end operatively connected to said free end of said link, said operating member when movable between said on and off positions operating said spring to move with a snap action said movable contact between said open and closed circuit positions, and means for causing operation of said movable contact from said closed position towards said open position and beyond said xed end of said link to reverse the bias of said over--center spring on said y ber having a range of movement between open and closed circuit positions, an operating member having a range of movement between on and oi positions, a link having one end mounted on a xed axis within said range of movement of Said'. switch member and the opposite free end operatively connected to said operating member,`

an over-center spring having one end connected to said switch member and'the opposite end operatively connected to said free end of said link, said operating member when moved between said on and off positions operating said spring to move with a snap action said switch member between said open and closed circuit positions, means for causing operation of said switch member from said closed position towards said open position and beyond said fixed end of said link to reverse the bias of said over-center spring on said link, said link thereupon operating said operating member from said on position towards said oi position, and means for bringing said operating member to a standstill midway 4of-`said on and 01T positions.

19. A ycircuit breaker comprising a switch member having a range of movement between open and closed circuit positions, an over-center spring connected at one end to said switch member, an operating handle\operable between on and oi positions for moving the opposite end of said over-center spring to operate said switch member between said open and said closed circuit positions with a snap action, a link pivotally supported at one end within the range of movement of said switch member, means forming a driving connection between the opposite end of said link and said operating handle, said link being provided with means intermediate its ends for engaging said switch member to initiate movement of said switch member towards one or the other of its positions at substantially the instant said over-center spring initiates said snap action movement of Asaid switch member.

20. A circuit breaker comprising a frame, a

switch member having a range of movement between open and closed circuit positions, an operating handle pivotally supported to said frame on one side of said range of movement for operation between on and oi positions, arovercenter spring connected at one end to said switch member for operating said member with a snap actiony between said open and closed circuit positions, a link having one end pivotally mounted on said frame on the opposite side of said range of movement of said switch member, said handle being provided with a radial slot, connecting means forming a driving .connection with the sides of said slot and supporting said opposite ends of said link and the opposite end of said over-center spring, said link being provided with means for rigidly `engaging said switch member to initiate movement of said switch member at substantially the' same instant said over-center spring applies its bias to said switch member to operate it with a snap action from one to the other of its positions.

21. A circuit breaker comprising a frame, a switchvmember having a range oi movement between open and closed circuit positions, an operating handle pivotally supported to said frame on one side of said rang of movement 'for operation between on and oi positions, an overcenter spring connected at one end to saidswitch member for operating said member with a snap action between said open and closed circuit positions, a link having one end-pivotally mounted on said frame on the opposite side of said range of movement of said switch member, said handle |`being provided with a radial slot, connecting means forming a driving connection with the sides of said slot and supporting said opposite ends of said link and the opposite end of said over-center spring, said link being provided with means for rigidly engaging said switch member to initiate movement of said switch member at substantially the same instant said over-center spring applies its bias'to said switch member toA tween open and closed circuit positions, an.oper

ating handle pivotally supported on said frame on one side of said range of movement for operation between on and oi positions, an over-center spring connected at one end to said switch member for operating said member with a snap action between said open and closed circuit positions, a link having one end pivotallymounted on said frame on the opposite side of said range of movement of said switch member, said handle being provided with a radial slot, connecting means forming a driving connection'- with the sides of said slot and supporting the opposite ends of said link and the opposite end of said over-center spring, said link being provided with means for rigidly engaging said switch member to initiate movement of said switch member at substantially the same instant said overcenter spring applies its bias to said switch member to operate it with a snap action from' one to the other of its positions, a guide member pivoted at one end and connected at its opposite end to said switch member, a tripping member normally biased for movement into engagement with said guide member for .operating said guide member and said switch member, from said closed circuit position to said open circuit position, overload responsive means normally restraining said tripping memberI in one vposition and operable upon the occurrence of a predetermined overload to release said tripping member the resulting movement of said movable contact carrying one end of said over-center spring beyond said fixed end of said link to reverse the bias of said over-center spring on said link, said link thereupon moving said' operating 'member from .its on position towards 'its oi position,'said tripping member forming a stop Nfor said operating handle to maintainit/in a.

position between said on and o' positions to indicate the over-load opening' of said circuit breaker. A

23.`.A circuit .breaker vcomprising aV switch member having a range ,i of movement between open and closed circuit positions, an over-center spring operatively connected at one 'end to said being operable between on and or positions, the opposite end of said over-center spring being supported by said free end of said link, and means operable upon movement of said link between said predetermined positions for rigidly engaging said movable switch member to initiate its movement between said open and closed circuit positions.

24. A circuit breaker comprising a switch member having a range of movement between open and closed circuit positions, an operating handle movable about a xed axis between on and oli positions, said handle being provided with a radial slot, a pair of llinks secured together at one end by apin which extends through said slot the opposite ends of said links being mounted for rotation about a xed axis located within the range of movement of said switch member, a guide member` having one end' movable about a fixed axis. and the opposite end connected to said switch member, and a pair of lover-center springs having the corresponding ends thereof supported by said pin and the opposite corresponding ends thereof operatively connected to said switch member oroperating said switch- 25. A circuit breaker comprising a switch meinber having a range of movement between open and closed circuit positions, an over-center spring Connected at one end to said switch member, a link having one end pivoted for rotation about a fixed axis substantially within and to one side of said range of movement of said switch inember, an operating handle movable between on and 01T positions about a fixed axis located on the opposite side of said range of movement, a guide member having one end movable about a iixed axis and the opposite end connected to said switch member, connecting means forming a lost motion driving connection between said handle and the opposite ends of said link and said over-center spring, and means for rigidly engaging said switch Amember to initiate its movement between said open and closed circuit positions comprising a slot formed in said link of such dimensions that said slot operatively engages said switch member at substantially the time said over-center spring moves past its dead center position.

DAVD C. PRECE. 

